The present invention relates to an apparatus for altering a display on an electronic display screen, and in particular to such apparatus that mimic nonelectronic apparatus. In particular, the present invention relates to apparatus for altering the display on an electronic display screen which mimics the characteristics of a paintbrush and paint palette.
The advent of the modern (lay computing machines has led to a proliferation of software programs that allow drafters, graphic designers, photo touch-up experts, and artists to practice their skills using a computer instead of traditional methods that are generally slower, less reproducible, and more expensive.
Machines such as the Xerox Star and Apple Macintosh introduced the concept of icon and mouse based computing to the general population. The main purpose of the icon and mouse was to eliminate the need to remember long complex instruction sequences that could be simply replaced by a point and click action of the mouse over an icon or menu selection. This methodology became prevalent in the middle to late 1980's and will probably remain so.
The light pen allows a user to input data to a computer by touching the pen directly to the display screen. The primary purpose of the light pen is the selection of menu items on the screen. In recent years, the light pen has also found application as an input device that simulates a drawing tool such as a pencil. The connection to the host computer is usually through a cable to a serial or parallel I/O port from the pen.
Typical processes required in a mouse-based drawing/painting program include a pencil-like tool, a fill-in tool, an eraser, a paintbrush, a spray can, a pencil, smudging tools, and sharpening tools. The program may also allow the user to select the shape and size of paintbrush represented by the mouse.
The mouse-based paintbrush suffers from a number of inherent drawbacks. First, there is poor feedback between the motions of the mouse and the actions on the screen, so that painting requires unnatural hand-eye coordination. Second, the mouse cannot provide pressure sensitive action, i.e. the artist does not have the luxury of being able to press lightly to create thin wispy strokes, or press firmly to create broad harsh strokes. Third, the mouse does not provide the ability to mix colors in any way analogous to a paintbrush. Although most software paint programs have a color picker, the picker generally only allows the user to select a single color from a group of colors displayed on the CRT. Fourth, mouse-based paintbrushes only have the capability of selecting a single color. A real paintbrush can hold a mix of colors, and the corresponding brush strokes may have a striking effect. Fifth, the long mouse movements generally translate to shorter on-screen movements. Thus a long paintbrush stroke must be achieved by several movements of the mouse.